As an important supplement to the terrestrial network, the Low Earth Orbit(LEO) satellite network is an important part of the future earth-earth integrated network. However, due to the high moving speed of LEO satellites and the long propagation distance of satellite-ground communication, large propagation delay is caused, therefore a new calculation strategy for the Timing Advance(TA) of the uplink in the satellite-ground communication background of LEO satellites is needed. Based on the satellite-earth communication scenario of LEO satellite, TA and its provisions in the protocol are introduced firstly. Then, according to the characteristics of LEO satellite, a timing advance calculation method of LEO satellite communication is proposed. The effectiveness of the proposed scheme is verified by simulation analysis, which provides a reference for the design of satellite-earth communication system of LEO satellite.